Deep in the Taoist I Ching discipline is a firing process of spiritul alchemy. The cauldron and furnance are the hexagrams Heaven and Earth, symbolizing energy and spirit, firmness and flexibility. The medicines are the hexagrams Water and Fire, symbolizing real knowledge and conscious knowledge.
Taking the Yang of Water and filling in the Yin of Fire, water and fire settle each other; it happens naturally without forced effort. This is using yin to seek yang so that they complete, balance and settle each other.
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